Here is another thing I do for ease of handling and stability with long or heavy lenses.

I attach a collapsed monopod with a large foam rubber grip to the camera and support the camera by the monopod grip with my left hand with the monopod butt in my stomach and only use the right hand to stabilize the camera and trip the shutter. This might be helpful for you. Also my camera/monopod combo balances exactly at the monopod grip, so it is convenient to carry the camera by the pod grip with my left arm hanging down at my side. This is a very comfortable way to carry the camera on long walks while birding.